TODAY   |  April 09, 2014

New pings picked up in Flight 370 hunt

Two more signals were detected overnight in the search for Flight 370, and an official says he’s “optimistic” the plane will be found. But officials say those sounds are getting weaker. NBC’s Tom Costello reports.

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>>> we've got some breaking news. new signals picked up in the indian ocean as crews race against time now to find malaysia air flight 370. nbc's tom costello is on the story again for us. tom, good morning.

>> the australian american team has picked up signals in this area yet again. this time the signals lasted five and a half minutes and seven minutes. and this part is important as well. it was picked up by the australian ship, the ocean shield, and the ocean shield is pulling this pinger locator two miles beneath the surface of the ocean . however, the signals were weaker than expected. that might suggest the batteries are starting to die. this morning, new clues in the 33-day hunt for flight 370.

>> ocean shield has been able to reacquire the signals on two more occasions.

>> overnight, australian search coordinators announced their ship ocean shield, equipped with the u.s. navy 's towed pinger locator, or tpl, picked up two more underwater pings like this on tuesday. after detecting two initial pings over the weekend. commanders say they're now confident the signals came from a man-made device.

>> it's consistent with a locator on a black box , so that's why we are more confident than we were before. but, we've got to lay eyes on it.

>> to do that, they'll need to detect more pings to narrow the search area. a challenging task with the battery weakening fast. only then can they map the ocean floor and hunt for wreckage.

>> the better ocean shield can define the area, the easier it will be for the autonomous underwater vehicle to subsequently search for aircraft wreckage.

>> this is one of the most remote areas of the indian ocean , and at 15,000 feet, the ocean depth is a huge challenge. the empire state building stands 1,250 feet tall. the maximum known death a sperm whale can dive, 3,200 feet. the titanic was found at 12,5000 feet of water. they found air france 44713,000 feet down. if it's there, flight 370 could be 15,000 feet below the ocean surface, nearly three miles down. meanwhile, the search for debris continues on the ocean surface and in the air, but more than a month after flight 370 disappeared. still not a single piece of wreckage.

>> the longer this goes, the harder it gets, but we've already eliminated a lot of the area and we're continuing to search area as we're assigned every day.

>> here's a look at the underwater terrain that they're dealing with. this is a volcanic plateau . it's called broken ridge. and the depth here is anywhere from one to nearly four miles. the trouble is it's never been thoroughly charted because it's so remote. because it's so remote and because it's so dark, the experts say it could take a week to three to even map this floor and photograph the floor to try to find the wreckage. savannah, back to you.

>> all right, tom. thank you